Refrigeration system and flow control device therefor

ABSTRACT

The embodiment of the invention disclosed herein is directed to a refrigerating apparatus of the type having a refrigerant capable of boiling under relatively low pressure to absorb heat and condensing under relatively high pressure to expell heat. The refrigerating apparatus includes a compressor having a high pressure outlet port and a low pressure inlet port. A condenser is connected to the high pressure outlet port of the compressor to receive pressurized refrigerant vapor to cool the same and condense it to refrigerant liquid. The output of the condenser is connected to an evaporator, which is located in a cooling compartment of a refrigerating apparatus, and wherein the high pressure refrigerant liquid is converted to low pressure gas. A flow control device is connected in the fluid line between the outlet port of the condenser and the inlet port of the evaporator. This flow control device has a first member for supplying a restricted fluid flow of refrigerant to the evaporator when the compressor is running and producing a high pressure at the outlet port thereof. However, the flow control device also includes a second structural combination of elements for supplying an unrestricted fluid flow of refrigerant to the evaporator when the compressor is not running. The flow control device further includes an orifice and fluid passage adjacent the first member to provide a cooling action of relative hot gas and liquid refrigerant being delivered to the evaporator, thereby increasing the efficiency of the refrigeration system.

United States Patent Skvarenina Mar. 18, 1975 REFRIGERATION SYSTEM AND FLOW CONTROL DEVICE THEREFOR [76] Inventor: John Skvarenina, 2639 W. Augusta, Chicago, 111. 60622 22 Filed: Junell, 1973 [21] Appl. No.: 369,055

Primary E.raminer-Meyer Perlin Attorney, Agent, or Firm-0lson, Trexler, Wolters, Bushnell & Fosse, Ltd.

[5 7] ABSTRACT The embodiment of the invention disclosed herein is directed to a refrigerating apparatus of the type having a refrigerant capable of boiling under relatively low pressure to absorb heat and condensing under relatively high pressure to expell heat. The refrigerating apparatus includes a compressor having a high pressure outlet port and a low pressure inlet port. A condenser is connected to the high pressure outlet port of the compressor to receive pressurized refrigerant vapor to cool the same and condense it to refrigerant liquid. The output of the condenser is connected to an evaporator, which is located in a cooling compartment of a refrigerating apparatus, and wherein the high pressure refrigerant liquid is converted to low pressure gas. A flow control device is connected in the fluid line between the outlet port of the condenser and the inlet port of the evaporator. This flow control device has a first member for supplying a restricted fluid flow of refrigerant to the evaporator when the compressor is running and producing a high pressure at the outlet port thereof. However, the flow control device also includes a second structural combination of elements for supplying an unrestricted fluid flow of refrigerant to the evaporator when the compressor is not running. The flow control device further includes an orifice and fluid passage adjacent the first member to provide a cooling action of relative hot gas and liquid refrigerant being delivered to the evaporator, thereby increasing the efficiency of the refrigeration system.

12 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION Description of the Prior Art In compression type refrigerating systems utilizing a capillary tube refrigerant control is well known and one of the most popular types of refrigerating systems used in present refrigerator and air conditioner devices. Briefly, in this kind of system a compressor is located in the base of the cabinet of a refrigerator and the liquid refrigerant flows from a condenser up through a liquid line which may pass through a filter or a dryer in route to a capillary tube just preceding the evaporator. From this filter or dryer the refrigerant flows through the capillary tube into the evaporator whereat the pressure of the liquid refrigerant is substantially reduced. The design of the capillary tube in such systems is such that it maintains a pressure difference while the compressor is operating. The compressor maintains a low pressure in the evaporator coil by having an inlet or suction side of the compressor connected directly thereto. The refrigerant is supplied to the evaporator and boils rapidly therein, as a result of low pressure, and absorbs heat from the evaporator coils. The vaporized refrigerant is drawn through the suction line back to the compressor, where it is compressed to a high pressure, and discharged into a condenser coil, where it is cooled, turns into a liquid, and flows back into the liquid line. This operation continues until the thermo static control device of the refrigerator has cooled sufficiently to turn off the electric motor operating the compressor.

In this type of prior art system a relatively high pressure exists between the outlet port and inlet port of the compressor for a period of time that it takes for the system to equalize as a result of bleed-through through the capillary tube.- Therefore, if for some reason the apparatus was inadvertently shut down by means other than the temperature sensing device, as for example, an electrical storm or unplugging of the electrical outlet of the refrigerator, and then electrical power applied immediately again thereto, the compressor would experience a tremendous back pressure and would not operate as a result. To prevent electrical failure of such compressor motors, thermooverload devices are used. Therefore, should the electrical power he turned off and restored within a relatively short time interval, the thermo-overload would kick out and prevent electrical damage to the compressor.

Another inherent characteristic of this type of refrigerating system is that self-defrosting features are relatively complex and expensive to incorporate. For example, one common type of self defrosting feature is to provide a substantially complete reversal of the refrigerating cycle, that is, operating the condenser as an evaporator and operating the evaporator as a condenser for a relatively short period of time. This then, causes any frost that may have accumulated on the evaporator to melt and be driven off by a suitable circulating fan or the like. This type of system requires a complicated valve control mechanism to provide reversal of the fluid flow paths through the evaporator and condenser while operating the compressor motor in the same direction. It will be understood that some of these systems may also include means for reversing the direction of operation of the compressor motor.

Still another complicated means of obtaining selfdefrosting heretofore utilized in the prior art is the more common electric heating devices inserted into the refrigerating compartment for heating the surface of the evaporator and associated components electrically. This is done by utilizing timing mechanisms which operate periodically, preferably when the refrigerating compressor motor is not running. In both instances the means for providing automatic defrosting of the refrigerating apparatus is relatively complex and expensive.

SUMMARY OF THE INVENTION It is therefore a feature of this invention to provide a new and improved refrigeration system which utilizes a unique flow control device which enables automatic defrosting of the evaporator section of the system without the use of electric heating coils or reversal of the refrigerating cycle.

Still another feature of this invention is the utilization of a flow control valve in a refrigerating system which substantially completely equalizes the pressure differential between the outlet and inlet ports of the compressor after the normal refrigerating cycle has terminated.

Briefly, the flow control device of this invention is located in the fluid line between the outlet of the condenser and the inlet of the evaporator devices of a refrigerator. The flow control device, when the compressor is running, provides a restricted fluid flow of refrigerant into the evaporator through a capillary tube in the normal manner heretofor utilized. However, when the compressor stops running the flow control valve, which has a movable float element sealing a relatively large port, provides a relatively large volume fluid flow path between the outlet of the condenser and the inlet of the evaporator. For an initial period of time, after the compressor has stopped, high pressure at the outlet of the compressor will cause relatively warm liquid refrigerant to flow through a relatively large fluid flow path into the evaporator and thereby automatically effect a defrosting action therein. This rapid transport of relatively warm refrigerant also substantially completely eliminates the possibility of back pressure problems within the compressor.

While this invention is related generally to improvements in structures and apparatus used primarily in the field of refrigeration, and more particularly to refrigerator devices of the domestic type, it will be understood that the novel aspects of this invention may be utilized in other fields such as air conditioning, de-humidifying, food treatment, and the like.

Many other features and advantages of this invention will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings wherein like reference numerals throughout the various views of the drawings are intended to designate similar elements or components.

BRIEF'DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of a conventional compression refrigeration system utilizing a capillary tube in the usual manner;

FIG. 2 illustrates an improved refrigerating system utilizing the flow control device in accordance with the principles of this invention;

FIG. 3 is an enlarge fragmentary sectional view showing the cooperation of elements of the flow control device of this invention;

FIG. 4 is a sectional view taken along line 44 of FIG. 3; and

FIG. 5 illustrates the flow control device of FIG. 3 in a reduced pressure operating condition whereby relatively warm refrigerant fluid is allowed to pass from the outlet of the condenser to the inlet of the evaporator.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS For a better understanding of the improvement in existing refrigerating systems which is obtained by the present invention reference is first made to FIG. 1 which illustrates a prior art conventional compression refrigerating system using a capillary tube refrigerant control, and which is designated generally by reference numeral 10. The refrigerating system includes a compressor 11 operated by an electric motor 12, here illustrated substantially diagrammatically. It will be understood that the compressor 11 can also be driven by other means such as gasoline engines or the like. The compressor 11 includes an inlet port 13 and an outlet port 14 which, in turn, is connected to a condenser element at the inlet port 17 thereof. The condenser 16 has an outlet port 18 in fluid communication with a filter and dryer section 19, located at the upper end of the refrigerating system. The output of the dryer 19 is connected to a capillary control tube 20 which, in turn, has its output end connected to the input of an evaporator section 21 at its inlet port 22. The outlet port 23 of the evaporator section 21 is then connected through a fluid communication line 24 to the inlet 13 of the compressor 11.

A thermal control element 26 is electrically coupled to a motor control circuit 28 over a line 27. The motor control circuit 28 is arranged for operation by a conventional alternating current power source as supplied thereto by a pair of current conductors 29. While alternating current is here illustrated as the preferred embodiment it will be understood that direct current motor devices can be used. The output of the motor control device 28 is coupled to the motor section 12 over a pair of current conductors 30 for controlling energization and de-energization of the motor in response to sensing the desired range of temperatures within the refrigerating apparatus by the thermal control element 26.

In operation, during the normal operating and refrigerating cycle, high pressure refrigerant gas and liquid flow up through the fluid line connected to the dryer and filter element 19. The refrigerant at the output of he dryer is of relatively high pressure, and in liquid form, as it is applied to the capillary tube 20. High pressure liquid refrigerant then passes through the capillary tube, wherein some of the refrigerant may convert into a gaseous form. The high pressure gas and liquid refrigerant material is applied to a-relatively large volume within the interior of the evaporator 21 thereby causing a substantial instanteous decrease in pressure applied to the refrigerant. This causes vaporization or boiling ofthe refrigerant within the evaporator. The heat of vaporization causes heat from within the interior of the refrigerating device to absorbed within the evaporator and thereby absorbed within the refrigerant material. The relatively hot low pressure refrigerant gas is pulled into the inlet 13 of the compressor 11, under a suction or reduced pressure, and compressed therein and delivered to the condenser as a high pressure gas. Heat from the refrigerant is then dissipated from the condenser and causes the gas to condense into a liquid within the lower portion of the condenser or within the return conduit line leading from the outlet port 18 to the filter and dryer 19. This is a normal operating cycle of the refrigerator.

During these normal operating condition of the re frigerating cycle the pressure at the outlet port 14 of the compressor may be as high as I30 to I50 pounds per square inch. On the other hand, the pressure at the inlet port may be negative pressure. This then causes a tremendous instantaneous back pressure when the compressor 11 is shut-down as a result of stopping or disconnection of power to the motor 12. If sufficient time elapses after shutdown of the motor 12 the entire system will balance as a result of the continuous fluid flow path between the output 14 of the compressor and the inlet 13. However, this takes several minutes, if not longer, to equalize or at least to have the pressure decrease sufficiently to insure easy rapid start-up of the motor 12 during a subsequent energization thereof. Also it is noted that no external means for providing automatic defrost is inherent in the simplified refrigerating system. All machines heretofore known in the art require additional external components to obtain automatic defrosting of the evaporator.

For a better understanding of the present invention, reference is now made to FIG. 2 which illustrates an improved refrigeration system utilizing the flow control valve of this invention and designated generally by reference numeral 40. Here the refrigerator system 40 includes a compressor 41 and an electric drive motor mechanism 42 coupled thereto by any suitable means. In the most preferred form of construction the compressors and drive motors are combined in a single sealed unit so as to eliminate the need of refrigerant seals at the output shaft of the compressor. The compressor unit 41 includes an inlet port 43 and an outlet port 44 in fluid communication with a condenser 46 at the inlet side 47 thereof.

Most advantageously, the output of the condenser 46 is connected via its output 48 through a conduit line into a flow control device 49 constructed in accordance with the principles of this invention. The output of the flow control device 49 is connected to a conduit and capillary tube combination structure 50 which, in turn, is connected to an inlet port 52 of an evaporator 51.

The flow control device 49 of this invention provides a first refrigerant fluid path therethrough and through a capillary tube, somewhat in the same manner as described with regard to the prior art structure of FIG. I, but in this instance the capillary tube is located within the conduit communicating between the inlet port 52 of the evaporator and the outlet side of the flow control device 49. The flow control device 49 has enlarged aperture means therein and valve control means for covering the aperture during a normal refrigerating cycle so that refrigerant passes into the evaporator substantially entirely as a result of refrigerant flow through the capillary tube and a small port 64. However, when the compressor motor 42 stops, by any means, the flow control device 49 opens the substantially enlarged aperture formed therein and allows substantially instantaneous communication between the flow control device 49 and the evaporator 51 through the enlarged volume or cross-sectional area of theconduit portion associated with the conduit and capillary combination 50. This will be described in more detail with regard to FIGS. 3, 4, and 5.

The outlet side 53 of the evaporator 51 is connected back to the inlet side 43 of the compressor 41 substantially in the same manner as with regard to the conventional prior art refrigerating system of FIG. 1.

In operation, the refrigerating cycle of the apparatus 40 functions substantially in the same manner as a conventional refrigerating system, the exception being that the conduit and capillary tube structure 50 provides substantially a triple flow path to the evaporator, with one flow path, during operation, through the capillary tube and port 64 and the other flow path, during shutdown, through the larger diameter conduit. When the compressor 41 ceases operation the flow control device 49 causes opening of an enlarged aperture formed therein which, in turn, provides unrestricted fluid communication between the high pressure output liquid line of the compressor and the inlet 52 of the evaporator 51. For a short period of time high pressure liquid refrigerant flows uniformly through the inlet and outlet portion of the evaporator thereby warming or providing a self-defrosting feature at the termination and start of each cycle of operation. Furthermore, should the compressor motor 42 again be energized, for any reason, after a relatively short interval of deenergization, the compressor will experience substantially no back pressure, or only a small back pressure, this only being in the order of several pounds more or less, as compared to 100 pounds or more under a normal condition, so that the thermal overload of the compressor is not energized.

Referring now to FIGS. 3, 4, and 5 the details of construction of one preferred embodiment of the flow control device of this invention is illustrated. Here the flow control device 49 includes a housing 56 in which is formed a cavity 57. In the illustrated embodiment the housing and corresponding cavity are cylindrical in configuration. however, it being understood that housings and cavities other than cylindrical can be incorporated. The housing 56 has an inlet side 57 which in fluid communication with the output of the condenser 46, FIG. 2. Also associated with the housing 56 is an outlet side 58 which, in turn, is operatively coupled to the conduit and capillary tube assembly 50. For example, the conduit portion 50a may be silver soldered or otherwise fastened to the outlet port 58, and the conduit portions 50a may be substantially of the same diameter tubing as is the tubing associated with the evaporator 51.

In the illustrated embodiment a dryer section 59 may be associated with the lowermost portion of the flow control device 49, it being understood that the dryer section may be located elsewhere, but in any event is to be located at a place where it will not interfere with the operation of the internal mechanism of the flow control device 49.

The upper end of the flow control device 49 has formed in the cavity thereof an end wall 60 through which is formed an aperture 61. Also formed within the cavity 57 is a float device 62 which moves freely upwardly and downwardly within the cavity as a result of pressure applied thereto by the refrigerant material as it leaves the outlet port 44 of the compressor 41, which float device 62 drops downwardly, as a result of gravity in the illustrated embodiment, to rapidly open the aperture 61 at the end of the refrigerating cycle. While the illustrated embodiment shows the float device 62 as being moved downwardly under the force of gravity, it will be understood that spring means or the like may be incorporated in the system thereby allowing it to be positioned within the refrigerating apparatus in orientations other than substantially vertical as illustrated in FIG. 2.

The inside diameter of the cavity 57 is of a predetermined size and the outside diameter of the float control device 62 is of a size substantially less than the diameter of the cavity 57 so as to provide an annular gap or space 63 about the periphery of the float device 62. The accumulative cross-sectional area of the space between the cavity wall and the float device 62 is to be substantially greater than the cross-sectional area of a flow maintenance aperture 61 formed in the end wall 60. Under normal operating conditions a differential pressure drop must be maintained on both sides of the float control device so as to insure that it will be in its raised position, as shown in FIG. 3. The small fluid flow through aperture 61, provides a hydrostatic pressure differential across the float control device 62 so as to maintain a needle valve, or other valve mechanism 66 associated therewith, in sealing contact with the aperture 61. A tube 67 is secured within the cavity 57 and extends substantially the length of the housing 56. The tube 67 receives an opening 68 formed within the float device 62, and provides a guide slide mechanism for the float device to travel upwardly and downwardly so as to maintain the seal device 66, which is here illustrated as a needle valve, in registry with the aperture 61. The tube 67 has the upper end thereof provided with capillary tube receiving means 69 so that the inlet portion of the capillary tube 50b can be fastened thereto by such means as silver soldering or the like.

.The length of the capillary tube 50b is one of the things that determines the pressure within the system and is sufficient to have the terminating end 70 thereof enter the inlet portion of the evaporator 51, whereupon high pressure refrigerant liquid is discharged into the evaporator as a low pressure fluid which vaporizes to absorb heat therefrom.

The flow of refrigerant through the orifice 64 is sufficient to provide a cooling action within the large diameter tube 50a, which may be considered as an extension of the evaporator. This cooling action also causes cooling of the relatively hot liquid and gas passing through the capillary tube 50b to improve the efficiency of the refrigeration system.

Positioned at the lower end of the body 56 is a stop I or retainer ring 70 which may have a plurality of annular disposed slots or flute members to allow easy passage of refrigerant therethrough when the refrigerating cycle stops and large volumes of relatively warm refrigerant material flows into the evaporator through the flow control device 49. As best seen in FIG. 5 the float member 62 is shown displaced from its original upward position so as to completely open the aperture 61. This then, allows a large volume of relatively slow moving warm refrigerant to be delivered to the evaporator as a result of the normal pressure buildup that exists when the compressor motor is deenergized.

During a normal operating cycle of conventional regrigerating apparatus the time required for pressure balance between the inlet and outlet ports of the compressor may be in the oder of 3 to 5 minutes, more or less. When utilizing the flow control valve of this invention this pressure differential will decrease more rapidly, in the order of about ten seconds to 1 minute, more or less, to substantially completely unload, or pressure equalize, the system. However, at the instant of shutdown, the compressive force of liquid or gas on float 62 becomes less, thus causing the float to drop, in effect allowing port 61 to open, raising the pressure and temperature in evaporator 51. The flow of warm refrigerant during this short period of time is relatively slow from the condenser into the evaporator and does not pass through the capillary restriction which is used during the refrigerating cycle. This, then also provides automatic defrosting of the evaporator when the system is shut down.

While a single specific embodiment of the present invention is illustrated herein it will be understood that variations and modifications as to size, shape, configuration, and the like, may be effected without departing from the spirit and scope of the novel concepts disclosed and claimed herein.

The invention is claimed as follows:

1. In a refrigerating apparatus of the type having a refrigerant capable of boiling under relatively low pressure to absorb heat and condensing under relatively high pressure to expel heat, the combination including: a compressor having a high pressure outlet port and a low pressure inlet port, a condenser having an inlet port in fluid communication with said high pressure outlet port of said compressor and further having a high pressure liquid refrigerant outlet port, an evaporator having an inlet port in fluid communication with said high pressure liquid refrigerant outlet port of said high pressure liquid refrigerant outlet port of said condenser and having an outlet port in fluid communication with said inlet port of said compressor, and a flow control device connected in the fluid line between the outlet port of said condenser and the inlet port of said evaporator, said fluid control device having first flow passage means for supplying a restricted fluid flow of refrigerant to said evaporator when said compressor is running and producing a high pressure at the outlet port thereof during a refrigerating cycle, said fluid control device further having second flow passage means independent of said first flow passage for supplying an unrestricted fluid flow of refrigerant to said evaporator when said compressor is stopped, said first flow passage means of said fluid control device includes a capillary tube having a terminating end extending into said evaporator whereat the high pressure liquid refrigerant is converted to low pressure gas refrigerant during the refrigerating cycle, said second flow passage means of said flow control device including a conduit connected between the outlet port of said condenser and the inlet port of said evaporator, said second flow passage means including fluid flow limiting means which directs the refrigerant within the system primarily through said capillary tube during the normal refrigerating cycle, and which directs the refrigerant within the system primarily through said conduit at the termination of said refrigeration cycle, whereby the inherent residual high pressure liquid at the outlet port of said condenser will flow substantially unrestricted into said evaporator to provide an automatic defrosting cycle and rapidly to provide a pressure balance within the refrigerating apparatus.

2. The refrigerating apparatus as set forth in claim 1. wherein said flow limiting means includes a chamber having an end wall at the down stream end thereof, said end wall having an aperture formed therethrough and valve means engaged with said aperture when said compressor is running, whereby refrigerant flow is substantially through said capillary tube.

3. The refrigerating apparatus as set forth in claim 2, wherein said valve means is formed of a float body within said chamber, and includes a tapered valve element arranged for engagement with said aperture so as to completely seal the aperture against fluid flow from said condenser when said compressor is running.

4. The refrigerating apparatus as set forth in claim 3, wherein said chamber is substantially cylindrical in configuration, said float body being cylindrical in configuration and having an outer diameter less than the inner diameter of said chamber to provide a fluid flow space between said chamber and said float body, said cylindrical float body being slidably carried within said chamber, and wherein said float body is moved within said chamber to cause said valve element to seal said aperture during the normal running cycle of the refrigerating apparatus.

5. The refrigerating apparatus as set forth in claim 4, further including a flow maintenance aperture formed in said end wall whereby fluid flow which passes between the spacing of said float body and said chamber will flow through said flow maintenance aperture to provide a predetermined amount of hydrostatic pressure on the opposite side of said float body to maintain said valve element in firm contact with said aperture during normal running cycle of the refrigerator thereby insuring a substantial fluid refrigerant path through said capillary tube and said flow maintenance aperture.

6. The refrigerating apparatus as set forth in claim 1, wherein said capillary tube is located within said conduit.

7. The refrigerating apparatus as set forth in claim 6, wherein the inlet end of said capillary tube is positioned within the chamber of said flow control device and wherein refrigerant fluid flow from the chamber is primarily through said capillary tube during the normal operating cycle of the refrigerating apparatus and wherein fluid flow through said conduit occurs when said second means is activated as a result of shutdown of said compressor thereby providing a large volume fluid path between said condenser and said evaporator to direct warm high pressure refrigerant into said evaporator for defrosting the same.

8. The refrigerating apparatus as set forth in claim 1, further including a dryer section formed within said chamber, said dryer section preceding said float valve.

9. A flow control device for use in a refrigeration system, comprising in combination, a body, a chamber formed within said body, an inlet port fashioned at one end of said body for connection to a condenser of the refrigeration system to which it is connected, an outlet port formed at the other end of said body and arranged for connection to an evaporator of a refrigeration system to which it is connected, an apertured end wall formed in said body, said end wall having capillary tube means associated therewith, and float means positioned within said cavity and including seal means associated therewith for engagement with said aperture, whereby fluid flow through said flow control device during a normal refrigerating cycle occurs through said capillary means when said float means has its valve means urged against said aperture, and wherein fluid flow through said flow control device is primarily through said inlet and outlet ports and said aperture when the normal operating cycle of the refrigerating system is stopped.

10. The flow control device according to claim 9, wherein said chamber is substantially cylindrical in configuration and said float means is cylindrical, said chamber having a predetermined inside diameter and said float means having a predetermined lesser outside diameter to provide a fluid flow spacing between the walls of said chamber and said float means, flow maintenance port formed within said end wall to insure fluid flow about said float member and through said flow maintenance port during normal operating conditions of a refrigerating cycle, and guide means formed within said body to maintain alignment of said seal means formed on said float means and said apertures to insure closure of said aperture when said float means is displaced as a result of refrigerant flow therethrough.

11. The flow control device as set forth in claim 10. wherein said guide means includes a tube extending substantially along the axis of said cylindrical body, said float means having an opening formed therein to receive said tube and to slide therealong as a result of movement of said float means, said capillary means being formed at one end of said tube and wherein fluid flow into said capillary is directed through said tube when said float means is actuated to seal said aperture. 12. The flow control device as set forth in claim 9, further including a dryer station formed within said body, said dryer station being downstream of said float member. 

1. In a rEfrigerating apparatus of the type having a refrigerant capable of boiling under relatively low pressure to absorb heat and condensing under relatively high pressure to expel heat, the combination including: a compressor having a high pressure outlet port and a low pressure inlet port, a condenser having an inlet port in fluid communication with said high pressure outlet port of said compressor and further having a high pressure liquid refrigerant outlet port, an evaporator having an inlet port in fluid communication with said high pressure liquid refrigerant outlet port of said high pressure liquid refrigerant outlet port of said condenser and having an outlet port in fluid communication with said inlet port of said compressor, and a flow control device connected in the fluid line between the outlet port of said condenser and the inlet port of said evaporator, said fluid control device having first flow passage means for supplying a restricted fluid flow of refrigerant to said evaporator when said compressor is running and producing a high pressure at the outlet port thereof during a refrigerating cycle, said fluid control device further having second flow passage means independent of said first flow passage for supplying an unrestricted fluid flow of refrigerant to said evaporator when said compressor is stopped, said first flow passage means of said fluid control device includes a capillary tube having a terminating end extending into said evaporator whereat the high pressure liquid refrigerant is converted to low pressure gas refrigerant during the refrigerating cycle, said second flow passage means of said flow control device including a conduit connected between the outlet port of said condenser and the inlet port of said evaporator, said second flow passage means including fluid flow limiting means which directs the refrigerant within the system primarily through said capillary tube during the normal refrigerating cycle, and which directs the refrigerant within the system primarily through said conduit at the termination of said refrigeration cycle, whereby the inherent residual high pressure liquid at the outlet port of said condenser will flow substantially unrestricted into said evaporator to provide an automatic defrosting cycle and rapidly to provide a pressure balance within the refrigerating apparatus.
 2. The refrigerating apparatus as set forth in claim 1, wherein said flow limiting means includes a chamber having an end wall at the down stream end thereof, said end wall having an aperture formed therethrough and valve means engaged with said aperture when said compressor is running, whereby refrigerant flow is substantially through said capillary tube.
 3. The refrigerating apparatus as set forth in claim 2, wherein said valve means is formed of a float body within said chamber, and includes a tapered valve element arranged for engagement with said aperture so as to completely seal the aperture against fluid flow from said condenser when said compressor is running.
 4. The refrigerating apparatus as set forth in claim 3, wherein said chamber is substantially cylindrical in configuration, said float body being cylindrical in configuration and having an outer diameter less than the inner diameter of said chamber to provide a fluid flow space between said chamber and said float body, said cylindrical float body being slidably carried within said chamber, and wherein said float body is moved within said chamber to cause said valve element to seal said aperture during the normal running cycle of the refrigerating apparatus.
 5. The refrigerating apparatus as set forth in claim 4, further including a flow maintenance aperture formed in said end wall whereby fluid flow which passes between the spacing of said float body and said chamber will flow through said flow maintenance aperture to provide a predetermined amount of hydrostatic pressure on the opposite side of said float body to maintain said valve element in firm contact with said aperture during normAl running cycle of the refrigerator thereby insuring a substantial fluid refrigerant path through said capillary tube and said flow maintenance aperture.
 6. The refrigerating apparatus as set forth in claim 1, wherein said capillary tube is located within said conduit.
 7. The refrigerating apparatus as set forth in claim 6, wherein the inlet end of said capillary tube is positioned within the chamber of said flow control device and wherein refrigerant fluid flow from the chamber is primarily through said capillary tube during the normal operating cycle of the refrigerating apparatus and wherein fluid flow through said conduit occurs when said second means is activated as a result of shutdown of said compressor thereby providing a large volume fluid path between said condenser and said evaporator to direct warm high pressure refrigerant into said evaporator for defrosting the same.
 8. The refrigerating apparatus as set forth in claim 1, further including a dryer section formed within said chamber, said dryer section preceding said float valve.
 9. A flow control device for use in a refrigeration system, comprising in combination, a body, a chamber formed within said body, an inlet port fashioned at one end of said body for connection to a condenser of the refrigeration system to which it is connected, an outlet port formed at the other end of said body and arranged for connection to an evaporator of a refrigeration system to which it is connected, an apertured end wall formed in said body, said end wall having capillary tube means associated therewith, and float means positioned within said cavity and including seal means associated therewith for engagement with said aperture, whereby fluid flow through said flow control device during a normal refrigerating cycle occurs through said capillary means when said float means has its valve means urged against said aperture, and wherein fluid flow through said flow control device is primarily through said inlet and outlet ports and said aperture when the normal operating cycle of the refrigerating system is stopped.
 10. The flow control device according to claim 9, wherein said chamber is substantially cylindrical in configuration and said float means is cylindrical, said chamber having a predetermined inside diameter and said float means having a predetermined lesser outside diameter to provide a fluid flow spacing between the walls of said chamber and said float means, flow maintenance port formed within said end wall to insure fluid flow about said float member and through said flow maintenance port during normal operating conditions of a refrigerating cycle, and guide means formed within said body to maintain alignment of said seal means formed on said float means and said apertures to insure closure of said aperture when said float means is displaced as a result of refrigerant flow therethrough.
 11. The flow control device as set forth in claim 10, wherein said guide means includes a tube extending substantially along the axis of said cylindrical body, said float means having an opening formed therein to receive said tube and to slide therealong as a result of movement of said float means, said capillary means being formed at one end of said tube and wherein fluid flow into said capillary is directed through said tube when said float means is actuated to seal said aperture.
 12. The flow control device as set forth in claim 9, further including a dryer station formed within said body, said dryer station being downstream of said float member. 